Piston-ring construction



Jan. 15, 1957 HSlA-Sl PlEN 2,777,740

PISTON-RING CONSTRUCTION Filed Jan. 22, 1954 4 Sheets-Sheet 2 INVENTOR.HSlA-Sl 'PIEN BY KW i ATTORNEY Jan. 15, 1957 HSlA-Sl PIEN 2,777,740

PISTON-RING CONSTRUCTION Filed Jan. 22, 1954 4 Sheets-Sheet 3 uINVENTOR. HSlA-SI PIEN ATTORNEY Jan. 15, 1957 HSlA-SI PIEN 2,777,740

PISTON-RING CONSTRUCTION Filed Jan. 22, 1954 4 Sheets-Sheet 4 INVENTOR.

HSlA-SI PIEN 5 E. ,2 m' NE) United States Presto PISTON-RINGCONSTRUCTION Hsia-si Pien, Drex el fill, Pa., assignor to WiikeningManufacturing Co., Philadelphia, Pa., a corporation of DelawareApplication January 22, 1954, Serial No. 405,565

Claims. (Cl. 30924) The present invention relates to certain new anduseful 3-piece piston-rings for internal combustion engines and the likeand to a novel spacer-and-expander for such type piston-rings. v

There has been a long-felt need for non-bottoming, self-expandingpiston-rings, namely piston-rings which exert an expansive forceirrespective of whether or not the piston-ring is in contact withthebottom of the ringreceiving groove, and which effect a uniformcircumferential engagement of the piston-ring sealers or rails againstthe cylinder walls.

Recently a number of such non-bottoming circumferentially expansiblepiston-rings have been developed which have achieved a more or lesssatisfactory level of performance. However by and large suchself-expanding piston-rings have been of relatively complex constructionand have required a large amount of bending and milling in theirfabrication. Moreover, due to their structural complexity suchheretofore developed piston-rings have in some instances developed poorperformance characteristics after a period of use, with thespacer-and-expander portion of the piston-ring becoming deformed andcausing malfunction.

This invention has as an object the provision of a nonbottomingcircumferentially expansible piston-ring which does not require anysupport and is capable of functioning for greatly protracted periods ina highly satisfactory manner.

Another object of the present invention is a piston-ring which willconform to the cylinder-wall notwithstanding any slight out-of-roundnessor out-of-cylindrical shape of the cylinder-wall due either todistortion of the cylinderwall or due to wear, and one which will breakin readily.

Another object of the present invention is a piston-ring which will bearagainst the cylinder-wall with uniform or equalized outward radialpressure and which will efiectively seal against the cylinder-wall andwhich may have a relatively high unit of contact-pressure per unit ofcontact-area with the cylinder-wall, and which will provide adequatelubrication with good oil control.

For the purpose of illustrating the invention, there are shown in theaccompanying drawings forms thereof which are at present preferred,although it is to be understood that the various instrumentalities ofwhich the invention consists can be variously arranged and organized andthat the invention is not limited to the precise arrangement andorganizations of the instrumentalities as herein shown and described.

In the accompanying drawings in which like reference characters indicatelike parts:

Figure 1 is an exploded perspective view of a threepiece piston-ring ofone embodiment of the present invention.

Figure 2 represents a side sectional view of the threepiece piston-ringshown in Figure l in position in the ringreceiving groove of a pistonwith the sealing-rings of the piston-ring contacting the cylinder-wall.i

Figure 3 is a plan view of a fragmentary portion of a cut strip of bandor ribbon of flat spring metal, such as spring-steel, from which thespacer-and-expander ofthe three-piece piston-ring of Figure 1 is formed,showing the first stage in the formation of the spacer-and-expander.

Figure 4 is an exploded perspective view of another embodiment of thethree-piece piston-ring of the present invention. v

Figure 5 represents a side sectional view of the threepiece piston-ringshown in Figure 4 in position in the ringreceiving groove of a pistonwith the sealing-rings of the pistonring contacting the cylinder wall.

I Figure 6 is a plan view of a fragmentary portion of a cut strip ofband or ribbon of flat spring-metal, such as spring-steel, from whichthe spacer-and-expander of the three-piece piston-ring of Figure 4 isformed, showing the first stage in the formation of thespacer-and-expander.

Figure 7 is an exploded perspective view of another embodiment of thethree-piece piston-ring of the present invention.

Figure 8 represents a side sectional view of the threepiece piston-ringshown in Figure 7 in position in the ring-receiving groove of a pistonwith the sealing-rings of the piston-ring contacting the cylinder-wall.

Figure 9 is a plan view of a fragmentary portion of a cut strip of bandor ribbon of flat spring metal, such as spring-steel, from which thespacer-and-expander of the three-piece piston-ring of Figure 7 isformed, showing the first stage in the formation of thespacer-and-expander.

Figure 10 is an exploded perspective view of another embodiment of thethree-piece piston-ring of the present invention.

Figure 11 represents a side sectional View of the threepiece piston-ringshown in Figure 10 in position in the ring-receiving groove of a pistonwith the sealing-rings of the piston-ring contacting the cylinder-wall.

Figure 12 is a plan view of a fragmentary portion of a cut strip of bandor ribbon of flat spring metal, such as spring-steel, from which thespacer-and-expander of the three-piece piston-ring of Figure 10 isformed, showing the first stage in the formation of thespacer-and-expander.

Referring to Figures 1 and 2 for one embodiment of the piston-ring ofthe present invention, the piston-ring shown therein comprises an upperor top thin flat sealingring, oil scraper or oil control ring element2%, a bottom or lower sealing-ring, oil scraper or oil control ringeleent 21, and a spacer-and-expander designated 22 comprising acontinuous axially corrugated circumferentially expansible ring havingits ends 19 abutting when the spacer-and-expander is operativelypositioned. The operative position of the spacer-and-expander is shownin Figure l where ends 19 are abutting. i

The axially corrugated spacer-and-expander 22 has a generally zig-zagconfiguration and includes sealing-ringengaging axial surfaces 23 at itsupper and lower peaks. designated 24. The sealing-ring-engaging amalsurfaces 23 when in operative position (see Figure 2) contact the inneredge 25 of the sealing-rings 20 and 21. Radially projecting tabs,fingers or projections 26 on the underside of peaks 14 comprise thesupporting or seating surfaces of spacer-and-expander 22 and spacesealing-rings 20 and 21 respectively against top side wall 27 andbottomside. wall 23 of ring-receiving groove 29 of piston 30, as shownin Figure 2. v

Each of sealing-rings 20 and 21, whichare referred to for the sake ofbrevity as a seal or .rail is preferably made of a flat band of steelalthough they may be formed from'other suitable hard drawn metal.

The sealing-rings 20 and 21 can be made by coiling a metal. band into a'coil of suitablev diameten'and'then cutting theindividualcouvolutionsto form the sealsjor by coiling such a band and cutting off eachconvolution as it is-formed.

The outer cylinder-contacting or contact-edges 31 of sealing-rings 20and 21 can be plated with chromium to provide for longer life.

The sealing-rings 20 and 21 are each split or provided with a gap 32, atone point, but are of such diameter that when the outer edge 31 of seals21) and 21 contacts the cylinder-wall 37 as shown in Figure 2, the gap32 is approximately closed. Sealing-ring gap 32 is formed when each sealis cut from the coil as indicated above.

The spacer-and-expander 22 is preferably made of spring-steel or otherspring metal. Thus a flat band 33 (see Figure 3) is recessed by cuttingaway the side edges to form a series of recesses or grooves 34, andprojections 26 alternately extending from either side but falling shortof the full width of band 33. These projections 26 are the spacerelements 26 in the finished spa-cer-and-expander 22. The uncut portionsof fiat band 33 comprise the pressure legs 18 and are of somewhatgreater length than the projections 26.

After fiat band 33 has been milled or punched to the form shown inFigure 3, tabs 26 are bent outwards in the same direction along dottedline 36 (see Figure 3) and the band is convoluted to form thespacer-'and-expander 22. Alternatively, if fiat band 33 requirestreatment, such as hardening, drawing and/ or tempering this can beaccomplished prior to or after effecting the cutting 'and/ or bending.

The axially corrugated spacer-and-expander 22 is nonbottomingcircumferentially compressible and when operatively positioned maintainssealing-rings 20 and 21 against cylinder-wall 37 (see Figure 2) at arelatively high unit of contact pressure per unit of contact area.

Good oil control is effected by oil passageways 34 formed by therecesses, slits or slots, in spacer-and-expander 22 intermediate 'thepressure legs 18. Thus, oil scraped from the cylinder-wall 37 bysealing-rings 20 and 21 during their reciprocal movement within thecylinder is removed through oil passageways 34 of the pistonrin-g intothe innermost portion of rin -receiving groove 29 from where it isremoved through drain hole 39 through the piston wall to the innerchamber of the piston and then to the crankcase.

The spacer tabs 26 may be positioned anywhere along the innerside ofpeaks 24 of spacer-and-expander 22 and may be of different widths. Thus,the width of spacer tabs 26 may be substantially co-extensive with thewidths of the peak 24 between the pressure legs 18, or more preferably,spacer tabs 26 may be of somewhat lesser width, as is shown in thedrawings. Spacer tabs 26 should be of such length so a to preventwobbling of rails 20 and 21 during the reciprocal movement of thepiston.

The spacerand-expander 22 can be modified, as by altering the anglesbetween pressure legs 18 and peaks 24, such as by varying the anglebetween the peak 24 and pressure legs 18. Alternatively, pressure legs18 may be widened and perforated to provide oil passagewaystherethrough.

In the embodiment of my invention shown in Figures 4 through 6, thespacer-and-expander 40 is provided with a modified form of spacerelementsv 41 and '42. However, in other respects the spacer-and-expander40 is similar to spacer-and-expander 22.

The spacer element 41 compn'ses a radially-extend- 4 vention achieves ahigh degree of spacing support for the rails.

The spacer-and-expander is formed from flat band 43, shown in Figure 6,by cutting the band along the lines shown, bending the spacer elements41 and 42 along the dotted lines and convoluting the band to produce thespacer-and-expander 40 heretofore described.

In the embodiment of my invention shown in Figures 7 through 9, thesp-acer-and-expander 45 comprises an xially corrugated slotted flat bandhaving rail-engaging tabs 46 at its peaks 47. Rail-engaging tabs 46extend axially beyond the outer surface '52 of peaks 47 ofspacerand-expander 45. The rail-engaging tabs 46, when operativelypositioned contact the inner edge 25 of sealingrings 21 and 21 (seeFigure 8). The outer surface 52 of peaks 47 serves as a seating surfaceand spacer element for sealing-rings 2d and 21. When spacer-and-expander45 is operatively positioned in ring-receiving groove 29 its free ends48 are abutting (as shown in Figure 7).

The spaccr-and-expander 45 is preferably slotted such as by slots 53within the body portion thereof to provide for more readycircumferential expan-sibility and compressibility.

The spacer-and-expander 45 is constructed from a flat slotted band (seeFigure 9) bearing tongues or tabs 46 alternately positioned thereon atregularly spaced intervals. Such tabs or fingers are bent along dottedlines 50. The band is axially orrugated in a sine-curve fash ion,forming peaks 47. The sealing-ring-engaging tabs 46 are formed bybending the projections 46 along dotted line 50, and the band isconvoluted to form the spacerand-expander 45. V

In the embodiment of my invention shown in Figures I 10 through 12, thespacer-and-expander 66 comprises ing tab 41 perpendicular to rin-engaging surface 23 of peak 24 and abutting a pressure leg 18. Spacerelement 42 is an angularly directed tab abutting the other pressure leg18 of the same peak 24. As seen in Figure 5, spacer element 41supports'the rail engaged by its peak 24, whereas spacer 42 extendsinwardly and furnishe support for the opposite raiL. This embodiment ofmy inan axially and radially corrugated fiat band having spacer tabs 68and rail-engaging tabs 70, the latter being axial extensions of theradial innermost portion 6? of spacerand-expander 66. In the embodimentshown in the drawings, three spacer tabs 68 are provided for eachrailengaging tab 70. Spacer tabs 68 project axially outwardly from thebody of spacer-and-expander 66 for a smaller distance than rail-engagingtabs 70. As seen in Figure 10, a spacer tab '68 is provided at theradial extremity of the radial corrugation with a spacer tab 68intermediate said radially outwardly disposed spacer tab and therail-engaging tab 70 with the outer axial surface 73 of each spacer tab68 serving as a seating surface for rails 20 and 21. i

The free ends 72 of spacer-and-expander 66 abut when spacer-and-expander77 is operatively positioned (as shown in Fig. 10).

The axial corrugations adjacent the tabs 68 and 70 provide oilpassageways. If desired, spacer-and-expander 66 may be slotted by axialspaced slots to provide additional oil passageways.

The spacer-and-expander 66 is milled or punched from a flat band (seeFigure 12) to yield rail-engaging tongues or tabs 70 positioned atregularly spaced intervals on both margins, with a plurality (in theembodiment shown, three) of spacer tabs 68 therebetween, and is thenradially corrugated and convoluted to form a finishedspacer-andexpander.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof, and it istherefore desired that the present embodiments be considered in allrespects as illustrative and not restrictive, reference being had to theappended claims rather than to the foregoing description to indicate thescope of the invention.

Having fully described my invention, 1 claim:

1. A composite 3-piece non-bottoming piston-ring adapted to be confinedwithin the ring-receiving groove of a piston comprising a pair ofparallel-spaced sealingrings adapted to be disposed closely adjacent thesidewalls of said ring-receiving groove, an axially corrugatedspring-meta spacer-and-expander disposed between a pair of sealing-ringswith its ends abutting each other, said spacer-and-expander comprisingan axially corrugated relatively thin member having radially outwardlyextending sealing-ring seating tabs extending from the innerside of itspeaks for a distance substantially greater than the cross-sectionalthickness of said peaks, the axially outermost surface of saidoutwardly-extending radial tabs comprising a supporting surface on whichthe sealing-rings are seated, the radially outer surface of the peaks ofsaid axially corrugated member which is juxtaposed to said radialsupporting surface overlapping and engaging the inner peripheral edgesof the sealing-rings, said sealing-rings and spacer-and-expander beingso constructed and arranged that when the sealing-rings are collapsed tosealing diameter and confined within the side-walls of saidring-receiving groove with the spacer-and-expander disposed between themand the aforesaid spacer-and-expander sealing-ring engaging outersurface engaged with the inner peripheral edges of said sealing-rings,the spacerand-expander will be compressed circumferentially and willurge the sealing-rings outwardly by means of the aforesaid ring-engagingsurfaces.

2. A composite 3-piece non-bottoming piston-ring adapted to be confinedwithin the ring-receiving groove of a piston comprising a pair ofparallel-spaced sealingrings adapted to be disposed closely adjacent thesidewalls of said ring-receiving groove, an axially corrugatedspring-metal spacer-and-expander disposed between said pair ofsealing-rings with its ends abutting each other, saidspacer-and-expander comprising an axially corrugated relatively thinmember having radially outwardly extending sealing-ring seating tabsextending from the inner side of its peak for a distance substantiallygreater than the cross-sectional thickness of said peaks, the axiallyoutermost surface of said outwardly-extending radial tabs comprising a.supporting surface on which the sealingrings are seated, the radiallyouter surface of the peaks of said axially corrugated member which isjuxtaposed to said radial supporting surface overlapping and engagingthe inner peripheral edges of the sealing-rings, oil passageways forremoving oil through said piston-ring, said sealing-rings andspacer-and-expander being so constructed and arranged that when thesealing-rings are collapsed to sealing diameter and confined within theside-walls of said ring-receiving groove with the spacerand-expanderdisposed between them and the aforesaid spacer-and-expander sealing-ringengaging outer surface engaged with the inner peripheral edges of saidsealingrings, the spacer-and-expander will be compressedcircumferentially and will urge the sealing-rings outwardly by means ofthe aforesaid ring-engaging surfaces.

3. A composite 3-piece non-bottoming piston-ring adapted to be confinedwithin the ring-receiving groove of a piston comprising a pair ofparallel-spaced sealingrings adapted to be disposed closely adjacent thesidewalls of said ring-receiving groove, an axially corrugatedspring-metal spacer-and-expander disposed between said pair ofsealing-rings with its ends abutting each other, saidspacer-and-expander comprising an axially corrugated relatively thinmember having a pair of radially outwardly extending sealing-ringseating tabs extending from the inner side of its individual peaks, oneof said pair of radially extending tabs being perpendicular to the planeof its peak and comprising a seating surface for the sealing-ringengaged by its peak, the other tab of said pair of radially extendingtabs being angularly directed inwardly and operatively engaging theopposite sealing-ring, the radially outer surface of the peaks of saidradially corrugated member which is juxtaposed to said radial supportingsurface overlapping and engaging the inner peripheral edges of thesealing-ringsysaid sealing-rings and spacer-and-expander being soconstructed and arranged that when the sealing-rings are collapsed tosealing diameter and confined within the side-walls of saidring-receiving groove with the spacer-and-expander disposed between themand the aforesaid spacer-and-expander sealing-ring engaging outersurface engaged with the inner peripheral edges of said sealing-rings,the spacerand-expander will be compressed circumferentially and willurge the sealing-rings outwardly by means of the aforesaid ring-engagingsurfaces.

.4. A spacer and-expander for multi-seal-piston-rings adapted tointervene a pair of sealing-rings and to maintain said pair ofsealing-rings disposed within the ringreceiving groove of a piston andurged outwardly comprising an axially corrugated spring-metalcircumferentially compressible relatively thin spacer-and-expanderhaving radially-outwardly extending sealing-ring seating tabs extendingfrom the inner side of its peaks for a distance substantially greaterthan the cross-sectional thickness of said peaks, the axially outermostsurface of said outwardly extending radial tabs comprising a supportingsurface for seating the sealing-rings, the radially outer surface of thepeaks of said axially corrugated member which is juxtaposed to saidradial supporting surface constructed and arranged to overlap and engagethe inner peripheral edges of the sealing-rings so that when saidspacer-and-expander is operatively engaged with said sealing-rings andcollapsed to cylinder diameter and confined within the side-walls ofthe'ring-receiving groove with the sealing-ring-engaging outer surfaceengaged with the peripheral edges of the sealing-rings, thespacer-andexpander will be compressed circumferentially and will urgethe sealing-rings outwardly by means of the aforesaid ring-engagingsurfaces.

5. A spacer-and-expander for multi-seal-piston-rings adapted tointervene a pair of sealing-rings and to maintain said pair ofsealing-rings disposed within the ring receiving groove of a piston andurged outwardly comprising an axially corrugated spring-metalcircumferentially compressible relatively thin spacer-and-expanderhaving a pair of radially-outwardly extending sealing-ring seating tabsextending from the inner side of its individual peaks, one of said pairof radially extending tabs being perpendicular to the plane of its peakand comprising a seating surface for the sealing-ring engaged by itspeak, the other tab of said pair of radially extending tabs beingangularly directed outwardly and adapted to operatively engage theopposite sealing-ring, the radially outer surface of the peaks of saidaxially corrugated member which is juxtaposed to said radial supportingsurface constructed and arranged to overlap and engage the innerperipheral edges of the sealing-rings so that when saidspacer-and-expander is operatively engaged with said sealing-rings andcollapsed to cylinder diameter and confined Within the side-walls of thering-receiving groove with the sealing-ring-engaging outer surfaceengaged withthe peripheral edges of the sealing-rings, thespacer-and-expander will be compressed circumferentially and will urgethe sealing-rings outwardly by means of the aforesaid ring-engagingsurfaces.

References Cited in the file of this patent UNITED STATES PATENTS2,220,948 Paton l Nov. 12, 1940 2,635,022 Shirk Apr. 14, 1953 2,637,607Olson May 5, 1953 FOREIGN PATENTS 555,348 Great Britain Aug. 18, 1943

